Making pollution sponges out of nanoparticles

Special sponges that can clean toxic pollutants from waterways are being developed by Australian scientists.

The sponges get their pollution absorbing powers from titanium dioxide—the same stuff that’s in your mineral sunscreen—which is cheap and abundant in Australia and environmentally safe to use.

It can be modified to collect toxic metal ions from water. And it can act as a photocatalyst, breaking down organic chemicals that it encounters.

But individual titanium dioxide nanoparticles are hard to control in solution.

Professor Rachel Caruso, Director of the Enabling Capability Platform for Advanced Materials at RMIT University, and her team have harnessed the nanoparticles’ powers by building them into controllable structures. They take sponge materials as a template, layer them with nanoparticles, and then remove the template, ending up with ‘nanoporous-sponges’.

Using this clever method, scientists have excellent control over the porosity and surface area of the material.

“If I’m putting this material into a polluted water stream, the more surface area I have, the more contact I have for collecting or reacting with the pollutant,” Rachel says.

Potential applications for these new nanoporous-sponges are in textile industries that use chemical dyes to colour fabrics and then need to clean the run-off. Dyes can be broken down into harmless molecules through contact with the nanoparticles.

“Rather than allowing that dye to pollute the water stream, you would treat the water before it is released,” Rachel says.

Other applications include soaking up environmental pollutants, or use in batteries and solar cells.

Nanoparticle sponges are being developed to clean toxic pollutants from waterways.